Silvia Americo
Ciclo: XXXVII
Data inizio: 31/10/2021
Curriculum: Agroalimentari
Borsa: PON – tematiche Green
Titolo tesi: : “A multiomic study to unveil the salt stress tolerance mechanisms in S. pennellii x S. lycopersicum Introgression Lines (ILs)”
Abstract: Salinity stress significantly disrupts plant metabolism leading to stunted development, reduced yield, and eventually to death. Crops have numerous wild relatives capable of growing under suboptimal conditions. Solanum pennellii, a wild tomato species endemic to the Andean region, thrives in arid and saline habitats, making it an ideal donor of resilience traits for cultivated tomato (Solanum lycopersicum). A collection of S. pennellii (LA1706) x S. lycopersicum (M82) introgression lines (ILs) were developed to assess the impact of specific genomic regions on plant phenotype. Several studies identified chromosome 7 of S. pennellii as a potential source of salt tolerance traits. The IL 7-4-1 (LA4068) was found as the most salt stress tolerant IL genotype.
This work aims to identify the mechanism responsible for the salt stress tolerance of IL 7-4-1 and the candidate genes involved, derived from S. pennellii and introgressed in the S. lycopersicum genome. To achieve this, we decided to proceed through a multiomic approach - including genomics, phenomics, transcriptomics and metabolomics.
The whole genome sequencing of chromosome 7’s ILs allowed to physically map the introgressed regions of the ILs along the chromosome, finally building a new physical map. Moreover, IL 7-4-1 displayed a surprisingly large introgression of about 59Mb. The phenotype analysis provided a quantitative confirmation of the visibly increased biomass and water retention capacity of this genotype, compared to its parental M82. Transcriptomics, through intragenotype comparisons, confirmed a minor sensitivity to salt stress of IL 7-4-1 than M82, while through the comparison of IL 7-4-1 and M82 in control condition was possible to identify several DEGs (Differentially Expressed Genes) associated with hormonal biosynthesis and cell morphology. Moreover, two candidate genes, ARF6b and CHY1, were identified within the comparison of IL 7-4-1 and M82 in control condition. The analysis of metabolites and lipids showed a clusterization of the compound according to the salt treatment, but not with the genotype. According to this is possible to hypothesize that the resilience of IL 7-4-1 derives from its enhanced growth capacity, regardless of the stress conditions. Finally, three constructs, two for the overexpression of the two candidates and one for the knock-out of ARF6b were designed and produced for the functional analysis of the candidate genes.
Approximately 59Mb of the tolerant S. pennellii genome present on chromosome 7 of IL 7-4-1 enhances the plant's growth and vigor, aligning with existing literature on its stress resistance. However, the large size of the introgressed region in IL 7-4-1 poses a challenge, as this complicates detailed analyses necessary for identifying individual candidate genes or QTLs useful for tomato breeding. This limitation can be overcome by creating a set of sub-ILs using IL 7-4-1 and M82 as parentals.
Tutor: Cattivelli
Data Conseguimento Titolo:
Linkedin: https://www.linkedin.com/in/silvia-americo-6956722bb
Email: silviamerico6@gmail.com
Periodi all'estero- Sede e data:1) Sequentia Biotech – Barcellona (Spagna) dal 13-10-2021 al 30-11-2021. 2) Max Planck Institute for Molecular Plant Physiology – Potsdam (Germania) dal 30-06-2023 al 20-12-2023.
Esperienze post-Dottorato ed attuale occupazione: